Thanks for all of those: I'll check them out. However, Machete doesn't fit for me: Grindhouse wasn't released as such in the U.K. so he is more like the main character in a short in the pseudo-trailer; even had it been, he would be a pseudo-main character rather than a supporting one. Good idea though.
How about the Jurassic Park franchise? Slightly tricky tho. If Sam Neill & Laura Dern are regarded as the leads & Jeff Goldblum & Richard Attenborough as supporting actors in JP1, then JP2 fits the bill because JG is the lead. Alternatively, if JP1 is regarded as an ensemble piece, then JP3 fits because SN is the lead.
It occurs to me that RA cameos in JP2 & LD cameos in JP3 if you ever decide you want to compile a complementary accolade about leading characters reappearing in later films as minor characters (altho of course there is the same issue about their relative status in JP1)...
Jurassic Park sounds a bit too much of a mess to wade through, and I don't view Jeff Goldblum's as a minor character in the first one, so I think it will be easiest to just leave that out. However, I like the idea of the complementary accolade and I'll do that.
Catwoman definitely doesn't fit. I'll check out Bruce and Lloyd -- thanks.
There was a Bruce and Lloyd short made for the DVD release - I know, because I reviewed it on here a while back, and then the film was (rightly) removed from the site because it was a DVD extra. So, that short exists, but the powers that be have decreed that it's not FWFR worthy.
The Hustler and Color of Money? Not exactly sure this works. Newman played Eddie Felson in both, first as the up-and-coming pool player then in the second, Cruise was the up-and-coming guy.